The opponent say he did not see the killing, so it means BA showed a different turn on his replay.
Nothing is more frustrating than, after a big strategy, and cost, you get the Pz killed, but next turn it doesn't appears in the killed units list and it's again in the field.
Not that turn, and I'm not sure if is in this game, but in I've seen in several occasions "Due to the update process, you may see different results than your opponent.".

